Applies to UNREACHABLE and UNIMPLEMENTED.
This helps track down the offending line more easily.

BUG=angleproject:2167

Change-Id: I97eb80677a6dd432a04f5e7516c3db3de8e7128a
Reviewed-on: https://chromium-review.googlesource.com/679999
Commit-Queue: Jamie Madill <jmadill@chromium.org>
Reviewed-by: Yuly Novikov <ynovikov@chromium.org>